RustFS: Missing admin authorization on notification target endpoints allows unauthenticated configuration of event webhooks

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

8.3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L

EPSS

• CVE-2026-40937: 0.29% estimated exploitation activity in the next 30 days; percentile 21.92 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Missing Admin Auth on Notification Target Endpoints in RustFS Finding Summary All four notification target admin API endpoints in rustfs/src/admin/handlers/event.rs use a checkpermissions helper that validates authentication only (access key + session token), without performing any admin-action authorization via validateadminrequest. Every other admin handler in the codebase correctly calls validateadminrequest with a specific AdminAction. This is the only admin handler file that skips authorization. A non-admin user can overwrite a shared admin-defined notification target by name, causing subsequent bucket events to be delivered to an attacker-controlled endpoint. This enables cross-user event interception and audit evasion. What Was Proven Live 1. Authorization bypass on all four endpoints (03readonlyuserbypass.py) - PUT, GET list, GET arns, DELETE all return 200 for readonly-user - Control routes (list-users, kms/status) correctly return 403 - Unauthenticated requests correctly…

Published by the source

22 Apr 2026, 19:24 UTC

Last modified by the source

27 Apr 2026, 16:22 UTC

Source last checked

26 Oct 2026, 15:42 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-pfcq-4gjr-6gjm

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# Patch Next advisory brief: CVE-2026-40937

Advisory: RustFS: Missing admin authorization on notification target endpoints allows unauthenticated configuration of event webhooks
IDs: CVE-2026-40937, GHSA-pfcq-4gjr-6gjm
Record: https://patchnext.com/advisories/cve-2026-40937 (revision 1, source checked 26 Oct 2026, 15:42 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io rustfs: affected <= 0.0.2

## Suggested inspection (read-only)
- crates.io rustfs: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on rustfs.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-pfcq-4gjr-6gjm (GitHub-reviewed advisory GHSA-pfcq-4gjr-6gjm lists affected ranges: crates.io rustfs >=0 <=0.0.2)

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